1. Field of the Disclosure
The present innovation relates generally to artificial visual systems and more particularly in one exemplary aspect to computer apparatus and methods for implementing spatial encoding in artificial retina.
2. Description of Related Art
Various existing implementations of artificial retinal functionality aim at converting visual input (e.g., frames of pixels) to output signals of different representations, such as: spike latency, see for example, U.S. patent application Ser. No. 12/869,573, filed Aug. 26, 2010, entitled “SYSTEMS AND METHODS FOR INVARIANT PULSE LATENCY CODING”, and U.S. patent application Ser. No. 12/869,583, filed Aug. 26, 2010, entitled “INVARIANT PULSE LATENCY CODING SYSTEMS AND METHODS SYSTEMS AND METHODS”; polychronous spike trains, see for example, U.S. patent application Ser. No. 13/117,048, filed May 26, 2011, entitled “APPARATUS AND METHODS FOR POLYCHRONOUS ENCODING AND MULTIPLEXING IN NEURONAL PROSTHETIC DEVICES”, current output, see for example, U.S. patent application Ser. No. 13/539,142, entitled “RETINAL APPARATUS AND METHODS” filed Jun. 29, 2012, each of the foregoing incorporated herein by reference in its entirety.
Artificial retinal apparatus (e.g., the apparatus described in U.S. patent application Ser. No. 13/152,119, Jun. 2, 2011, entitled “SENSORY INPUT PROCESSING APPARATUS AND METHODS”, incorporated herein by reference in its entirety) attempt to mimic particular spatial characteristics (horizontal connectivity) of natural retina cone cells, such as two-dimensional “difference-of-Gaussians” (DoG) spatial filter profile, and a difference filter in the temporal domain. In order to improve response to contrast changes and facilitate detection of edges, existing artificial retina implementations implement difference-of-Gaussians” spatial filter profile in the ganglion later (RGCs). Typically, the centers of the RGCs are arranged spatially as a two-dimensional (2-D) or a 3-dimensional (3D) structure, such as a linear array, a rectangle, square, or honeycomb pattern. The spatial extents of the RGCs, in terms of the input image pixels, may overlap with multiple neighboring RGCs.
It is often desirable, in, for example, retinal implant applications, to be able to reproduce various features (e.g., trichromatic vision, multiple levels of spatial and/or temporal resolution. Furthermore, it may be desirable to provide visual encoding apparatus that may be optimally configured (e.g., comprise different types of encoder neurons) for different applications, using the same general architecture.
In some applications, it may be beneficial to peorm data compression by utilizing conversion of real-valued (e.g., continuous and/or discrete with variable bit-length) signals into spike output.
Accordingly, there is a salient need for an improved apparatus and methods for encoding of visual data into spike output using spiking neuron networks.